JPWO2007037177A1 - Variable valve gear - Google Patents

Abstract

A variable valve apparatus having a switching mechanism for switching between a variable valve state and a variable valve state is intended to improve the durability of the switching mechanism. During idling before starting the vehicle, the operating state of the internal combustion engine is in the one-valve small lift region (point A). At this time, the one-valve variable state is set. After the vehicle starts, the driving state changes from point A → B → C and shifts to the double-valve large lift region. Thereafter, to shift up, when the clutch is disengaged and the accelerator pedal is released, the operating state returns to point A in the one-valve small lift region. In this case, since the time in the both-valve large lift region is short and the actual benefit of switching to the both-valve variable state is small, the switching operation to the both-valve variable state is prohibited at the point B → C.

Description

  The present invention relates to a variable valve operating apparatus, and more particularly to a variable valve operating apparatus capable of mechanically changing the valve opening amount.

  2. Description of the Related Art Conventionally, as described in Patent Document 1, for example, a variable valve device that mechanically changes a lift amount and a working angle of a valve according to an operation state of an internal combustion engine is known.

  In the variable valve operating apparatus described in Patent Document 1, two rotary cams are arranged on the cam shaft, and of the two intake valves arranged in the same cylinder, the first intake valve is driven to open and close by the first rotary cam. The second intake valve is opened and closed by a second rotating cam. A variable valve transmission mechanism constituted by a four-bar linkage mechanism is disposed between the first rotary cam and the first intake valve and between the second rotary cam and the second intake valve. .

  The four-bar linkage mechanism of the variable valve device includes an input arm having an input portion that contacts the rotating cam, a transmission arm that is swingably connected to the input arm, a swingable connection to the transmission arm, and a rotation control A swing arm that is swingable about an axis and that transmits a driving force transmitted from a rotating cam to an output unit that opens and closes an intake valve; It is composed of a control arm that is slidably connected. By controlling the attitude of the four-bar linkage mechanism and changing the relative position between the rotary cam and the input unit, the operating angle and lift amount of the intake valve can be mechanically changed.

  Further, the variable valve device includes a connection mechanism that connects a four-bar linkage mechanism (first link mechanism) related to the first intake valve and a four-bar link mechanism (second link mechanism) related to the second intake valve; There is provided a mechanism for maintaining the posture of the second link mechanism in a posture in which the operating angle of the second intake valve becomes a maximum value when the connection is released. The connection mechanism includes a through hole formed in the control arm of each four-bar linkage mechanism and a connection pin inserted into the through hole. The mechanism for maintaining the posture of the second link mechanism when the connection is released includes a through hole formed in the fixed plate, a through hole formed in a control arm (second control arm) of the second link mechanism, It consists of a connecting pin.

  The connecting pin is always engaged with the through hole of the second control arm, and is also fixed to the control arm (first control arm) side of the first link mechanism while being engaged with the through hole of the second control arm. It can also be moved to the plate side. When the connecting pin moves to the first control arm side and is inserted into the through hole of the first control arm, the second control arm is connected to the first control arm via the connecting pin. By connecting the control arms, the first link mechanism and the second link mechanism always take the same posture. Therefore, in this case, the first valve and the second valve can be controlled to the same valve opening amount.

  On the contrary, the second control arm is connected to the fixed plate via the connecting pin by the connecting pin moving to the fixed plate side and being inserted into the through hole of the fixed plate. By connecting the second control arm and the fixed plate, the posture of the second link mechanism is fixed to a fixed posture. In this case, only the valve opening amount of the first valve is controlled in a state where the valve opening amount of the second valve is fixed by changing the relative position between the rotary cam and the input unit by controlling the attitude of the first link mechanism. Can be changed mechanically.

  In other words, according to the variable valve operating apparatus, the opening amount of the first intake valve and the second intake valve is made the same, and the opening amount of the first intake valve and the second intake valve are made different. Can be selectively executed. Thereby, by making the valve opening amount of the first intake valve and the second intake valve different, particularly the lift amount of each valve, it is possible to make the intake flow rate different and generate a swirl (swirl flow) in the combustion chamber. Thus, it becomes possible to stabilize the combustion in the combustion chamber.

Japanese Unexamined Patent Publication No. 2004-1000055

  As described above, according to the above variable valve operating apparatus, both the variable valve state in which both the opening amounts of the first and second intake valves can be changed and the opening amount of the second intake valve are fixed. It is possible to switch to a one-valve variable state that changes the valve opening amount of only the first intake valve. When switching from the two-valve variable state to the one-valve variable state, two operations are required: an operation of removing the connecting pin from the pin hole of the first control arm and an operation of inserting the connecting pin into the pin hole of the fixed plate. . In addition, when switching from the single valve variable state to the double valve variable state, two operations are required: an operation of removing the connection pin from the pin hole of the fixed plate and an operation of inserting the connection pin into the pin hole of the first control arm. It becomes.

  In the internal combustion engine as described above, the two-valve variable state and the one-valve variable state are switched according to the operating state. For example, in the low rotation / low load range, there is a requirement to improve combustion by forming a swirl in the cylinder. Therefore, both valves are in a variable state. That is, the control device for the internal combustion engine stores a rule for distinguishing between the two-valve variable region that should be in the both-valve variable state and the one-valve variable region that should be in the one-valve variable state in the operating region, If the operating state of the internal combustion engine changes across the boundary between both regions, switching between the two-valve variable state and the one-valve variable state is performed accordingly.

  However, if the switching between the two-valve variable state and the one-valve variable state is frequently performed, the wear of the above-described connecting pins and pin holes constituting the switching mechanism progresses early, which adversely affects the durability of the switching mechanism. It is easy to affect. In addition, if switching is performed frequently, the switching operation may fail. If the switching operation fails, the original valve opening characteristics cannot be obtained, and the desired performance cannot be exhibited from the viewpoint of fuel consumption and drivability.

  The present invention has been made in view of the above points, and in a variable valve apparatus having a switching mechanism that switches between a variable valve state and a variable valve state, a variable valve that can improve the durability of the switching mechanism. An object is to provide a valve device.

In order to achieve the above object, a first invention is a variable valve gear,
A both-valve variable state in which the opening amounts of both the first valve and the second valve of the same type provided in the same cylinder are continuously variable; and the opening amount of the first valve is continuously variable; A valve mechanism having a switching mechanism for switching between a one-valve variable state in which the valve opening amount of the second valve is fixed;
Storage means for storing a rule for distinguishing between the two-valve variable region to be in the both-valve variable state and the one-valve variable region to be in the one-valve variable state among the operation region of the internal combustion engine,
Normal control means for causing the switching mechanism to perform a switching operation according to the rules;
Situation in which it is determined that a predetermined situation is expected to return to the original region in a short time when the operating state of the internal combustion engine shifts from one of the two-valve variable region and the one-valve variable region to the other Judgment means,
When the predetermined situation is established, prohibiting means for prohibiting the switching operation;
It is characterized by providing.

The second invention is the first invention, wherein
The predetermined condition is a condition within a predetermined time from the time of execution of a shift of a transmission interposed between the internal combustion engine and a drive wheel of a vehicle.

The third invention is the first invention, wherein
The predetermined condition is a condition in which a shift position of a transmission interposed between the internal combustion engine and a drive wheel of a vehicle is in a neutral or parking range.

According to a fourth invention, in any one of the first to third inventions,
After the operating state of the internal combustion engine has shifted from one of the two-valve variable region and the one-valve variable region to the other, if the specified region has not returned to the original region after a lapse of time, the prohibition of the switching operation is canceled. And a prohibition canceling means.

According to a fifth invention, in any one of the first to fourth inventions,
Measuring means for measuring the number of prohibitions by the prohibiting means or the cumulative time of prohibition;
When the number of times of prohibition or the cumulative time of prohibition exceeds a predetermined value, even if the predetermined situation is established, the permitting means for allowing the switching operation of the switching mechanism,
It is characterized by providing.

According to a sixth invention, in any one of the first to fifth inventions,
The valve opening amount limiting means for limiting the target valve opening amount when the switching operation is prohibited by the prohibiting means is further provided.

The seventh invention is the sixth invention, wherein
The valve mechanism is
A main cam that drives both the first valve and the second valve when in the two-valve variable state, and that drives only the first valve when in the one-valve variable state;
A sub-cam for driving the second valve when the one-valve variable state;
Including
The valve opening amount limiting means is configured such that when the switching operation from the one-valve variable state to the both-valve variable state is prohibited by the prohibiting means and maintained in the one-valve variable state, the sub cam and its counterpart member The target valve opening amount is limited to a range that does not separate from each other.

  According to the first invention, it is possible to switch between the two-valve variable state and the one-valve variable state by the switching mechanism. This switching operation is performed according to a rule for dividing the both-valve variable region and the one-valve variable region according to the operating state of the internal combustion engine. However, when the operating state has shifted from one of the two-valve variable region and the one-valve variable region to the other, when a predetermined situation is expected to return to the original region in a short time, Switching operation is prohibited. For this reason, according to this invention, it can avoid performing unnecessary switching operation | movement and can reduce the frequency of switching operation | movement. Therefore, wear and damage of the switching mechanism can be suppressed, and durability of the switching mechanism can be improved. In addition, since the possibility of failure in the switching operation can be reduced, it is possible to always realize the valve opening characteristics according to the operation state, and to reliably obtain good fuel consumption characteristics, exhaust characteristics, and drivability. it can.

  According to the second aspect of the invention, it is possible to reliably avoid an unnecessary switching operation that is likely to occur immediately after the transmission is shifted. For this reason, the frequency of the switching operation during traveling can be reduced.

  According to the third aspect of the invention, it is possible to reliably avoid unnecessary switching operation during free accelerator operation (so-called idling) performed when the transmission is in the neutral or parking range state. For this reason, the frequency of the switching operation in the free accelerator operation can be reduced.

  According to the fourth aspect of the present invention, when the operating state of the internal combustion engine shifts from one of the variable valve variable region and the variable valve variable region to the other, and does not return to the original region in a short time, the switching operation is performed. It is possible to cancel the prohibition and execute the switching operation. For this reason, even if the switching operation is expected to be unnecessary, the switching operation can be executed when the switching operation is actually required, and a suitable valve opening characteristic can be realized. Can do.

  According to the fifth aspect of the invention, even when a situation where the switching operation is expected to be unnecessary is established when the switching operation is prohibited or the prohibited cumulative time exceeds a predetermined value. The switching operation can be executed. Thereby, in any situation, a switching operation with a frequency necessary for maintaining the function of the switching mechanism can be executed. For this reason, it is possible to prevent adverse effects such as the switching mechanism sticking due to long-time non-operation.

  According to the sixth aspect, the target valve opening amount can be limited when the switching operation between the both-valve variable state and the one-valve variable state is prohibited. For this reason, generation | occurrence | production of the bad effect (for example, noise etc.) accompanying prohibition of switching operation | movement can be prevented reliably.

  According to the seventh invention, when the valve operating mechanism is in the variable state of both valves, both the first valve and the second valve are driven, and in the variable state of the one valve, the main cam that drives only the first valve; In the case of including the sub-cam that drives the second valve in the variable state, the switching operation from the one-valve variable state to the both-valve variable state is prohibited and the one-valve variable state is maintained. The target valve opening amount can be limited to a range in which the side member is not separated. For this reason, it is possible to reliably prevent re-contact (collision) between the separated sub cam and the counterpart member, so that noise is generated by the impact, or the surface of the sub cam or the counterpart member is damaged. This can be prevented more reliably.

It is a figure for demonstrating the structure of the system provided with the variable valve apparatus of Embodiment 1 of this invention. It is a perspective view for demonstrating the structure of the valve mechanism provided with the variable valve apparatus of this embodiment. It is a figure for demonstrating the structure of the variable valve mechanism in the valve mechanism shown in FIG. It is a disassembled perspective view which shows the variable valve mechanism and fixed valve mechanism which are shown in FIG. It is the schematic which shows the structure of the hydraulic system for operating a switching pin. It is a figure which shows the switching map of a both-valve variable state and a single valve variable state. It is a figure which shows the switching map of a both-valve variable state and a single valve variable state. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a flowchart of the routine performed in Embodiment 3 of the present invention. It is a figure which shows the valve lift (lift curve) of a 1st intake valve and a 2nd intake valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Piston 4 Cylinder block 5 Crankshaft 6 Crank angle sensor 8 Cylinder head 10 Combustion chamber 11 Spark plug 12 Intake port 14 Intake valve 15 Intake camshaft 16, 17 Intake cam 18 Variable valve apparatus 19 Intake passage 20 Injector 21 Surge tank 22 Throttle valve 23 Throttle motor 24 Accelerator opening sensor 25 Throttle opening sensor 26 Air flow meter 27 Air cleaner 28 Exhaust port 30 Exhaust passage 31 Air-fuel ratio sensor 35 Rocker arm 36 Rocker roller 37 Hydraulic lash adjuster 38 Lost motion spring 40 Variable valve mechanism 41 Control shaft 42 Control arm 43 Bolt 44 Intermediate arm 45 Pin 50 Oscillating cam arm 52 First roller 53 Second roller 4 connecting shaft 60 ECU
62 shift position sensor 70 fixed valve mechanism 71 large lift arm 72 arm coupling mechanism 73 input roller 74 switching pin 75 hydraulic chamber 76 pin hole 77 return spring 78 piston 81 oil passage 82 pump 83 discharge passage 84 discharge valve 85 orifice

Embodiment 1 FIG.
[System configuration]
FIG. 1 is a diagram for explaining the configuration of a system including the variable valve operating apparatus according to the first embodiment of the present invention. The system according to the first embodiment includes an internal combustion engine 1 mounted on a vehicle as a power source. The internal combustion engine 1 has a plurality of cylinders 2. FIG. 1 shows only one cylinder among a plurality of cylinders.

  The internal combustion engine 1 includes a cylinder block 4 in which a piston 3 is housed in a cylinder. The piston 3 is connected to the crankshaft 5 via a connecting rod. A crank angle sensor 6 is provided in the vicinity of the crankshaft 5. The crank angle sensor 6 is configured to detect the rotation angle of the crankshaft 5.

  A cylinder head 8 is assembled to the upper part of the cylinder block 4. A space from the upper surface of the piston 3 to the cylinder head 8 forms a combustion chamber 10. The cylinder head 8 is provided with a spark plug 11 that ignites the air-fuel mixture in the combustion chamber 10.

  The cylinder head 8 includes an intake port 12 that communicates with the combustion chamber 10. An intake valve 14 is provided at a connection portion between the intake port 12 and the combustion chamber 10. A valve operating mechanism 18 is provided between the intake valve 14 and the intake cam 16 of the intake camshaft 15. Details of the valve mechanism 18 will be described later.

  An intake passage 19 is connected to the intake port 12. In the vicinity of the intake port 12, an injector 20 that injects fuel into the intake port 12 is provided. A surge tank 21 is provided in the middle of the intake passage 19.

  A throttle valve 22 is provided upstream of the surge tank 21. The throttle valve 22 is an electronically controlled valve that is driven by a throttle motor 23. The throttle valve 22 is driven based on the accelerator opening AA detected by the accelerator opening sensor 24. A throttle opening sensor 25 is provided in the vicinity of the throttle valve 22. The throttle opening sensor 25 is configured to detect the throttle opening TA. An air flow meter 26 is provided upstream of the throttle valve 22. The air flow meter 26 is configured to detect the intake air amount Ga. An air cleaner 27 is provided upstream of the air flow meter 26.

  The cylinder head 8 includes an exhaust port 28 that communicates with the combustion chamber 10. An exhaust valve 29 is provided at the connection between the exhaust port 28 and the combustion chamber 10. An exhaust passage 30 is connected to the exhaust port 28. The exhaust passage 30 is provided with an air-fuel ratio sensor 31 that detects an exhaust air-fuel ratio.

  The system according to the present embodiment includes an ECU (Electronic Control Unit) 60 as a control device. In addition to the ignition plug 11, the valve operating mechanism 18, the injector 20, the throttle motor 23, a discharge valve 84 (see FIG. 5), which will be described later, and the like are connected to the output side of the ECU 60. A crank angle sensor 6, a throttle opening sensor 25, an accelerator opening sensor 24, an air flow meter 26, an air-fuel ratio sensor 31 and the like are connected to the input side of the ECU 60. The ECU 60 performs overall control of the internal combustion engine such as fuel injection control and ignition timing control based on the output of each sensor.

  A transmission (not shown) is interposed between the internal combustion engine 1 and the drive wheels of the vehicle. The ECU 60 is further connected with a shift position sensor 62 for detecting the shift position of the transmission. The transmission may be either a manual transmission or an automatic transmission.

[Configuration of variable valve gear]
FIG. 2 is a perspective view for explaining the configuration of the valve operating mechanism 18 provided in the variable valve operating apparatus of the present embodiment.

  As shown in FIG. 2, the intake camshaft 15 is provided with two intake cams 16 and 17 per cylinder. Two first intake valves 14L and second intake valves 14R are arranged symmetrically about the first intake cam 16. Between the first intake cam 16 and the intake valves 14L and 14R, variable valve mechanisms 40L and 40R are provided, respectively, which link the lift movement of the intake valves 14L and 14R with the rotational movement of the first intake cam 16. Yes. On the other hand, the second intake cam 17 is arranged so as to sandwich the second intake valve 14R between the first intake cam 16 and the second intake cam 16. A fixed valve mechanism 70 is provided between the second intake cam 17 and the second intake valve 14R to link the lift movement of the second intake valve 14R with the rotational movement of the second intake cam 17. The valve mechanism 18 is configured to selectively switch the interlocking destination of the lift of the second intake valve 14R between the variable valve mechanism 40R and the fixed valve mechanism 70.

(1) Detailed Configuration of Variable Valve Mechanism FIG. 3 is a view for explaining the configuration of the variable valve mechanism 40 in the valve mechanism 18 shown in FIG. Specifically, FIG. 3 is a view of the variable valve mechanism 40 as viewed from the axial direction of the intake camshaft 15. The left and right variable valve mechanisms 40L and 40R are basically symmetrical with respect to the first intake cam 16, and therefore the left and right variable valve mechanisms 40L and 40R are not distinguished here. Will be explained. In the present specification and drawings, when the left and right variable valve mechanisms 40L and 40R are not distinguished, they are simply referred to as the variable valve mechanism 40. Similarly, the component parts of the variable valve mechanisms 40L, 40R and the symmetrically arranged parts such as the intake valves 14L, 14R are distinguished from each other except when it is necessary to distinguish between them. The symbol is not attached.

  As shown in FIG. 3, the valve mechanism 18 has a rocker arm 35 that presses the intake valve 14 in the opening direction. The variable valve mechanism 40 is interposed between the first intake cam 16 and the rocker arm 35. The variable valve mechanism 40 is configured to continuously change the interlocking state between the rotational motion of the first intake cam 16 and the rocking motion of the rocker arm 35.

  The variable valve mechanism 40 has a control shaft 41 disposed in parallel with the intake camshaft 15. A control arm 42 is fixed to the control shaft 41 with bolts 43. A part of the control arm 42 protrudes in the radial direction of the control shaft 41. An intermediate arm 44 is attached to the protruding portion of the control arm 42 by a pin 45. The pin 45 is disposed at a position eccentric from the center of the control shaft 41. Therefore, the intermediate arm 44 is configured to swing around the pin 45.

  A swing cam arm 50 is swingably supported on the control shaft 41. The swing cam arm 50 has a slide surface 50 a on the side facing the first intake cam 16. The slide surface 50 a is formed so as to contact the second roller 53. The slide surface 50a is formed in a curved surface such that the distance from the first intake cam 16 gradually decreases as the second roller 53 moves from the distal end side of the swing cam arm 50 toward the axial center side of the control shaft 41. ing. Further, the swing cam arm 50 has a swing cam surface 51 on the opposite side of the slide surface 50a. The rocking cam surface 51 has a non-acting surface 51a formed so that the distance from the rocking center of the rocking cam arm 50 is constant, and the position away from the non-working surface 51a is closer to the axis of the control shaft 41 It is comprised with the action surface 51b formed so that distance may become far.

  A first roller 52 and a second roller 53 are disposed between the slide surface 50 a and the peripheral surface of the first intake cam 16. More specifically, the first roller 52 is disposed so as to contact the peripheral surface of the first intake cam 16. The second roller 53 is disposed so as to contact the slide surface 50 a of the swing cam arm 50. Both the first roller 52 and the second roller 53 are rotatably supported by a connecting shaft 54 fixed to the tip of the intermediate arm 44. Since the intermediate arm 44 swings around the pin 45 as a fulcrum, the rollers 52 and 53 also swing along the slide surface 50 a and the peripheral surface of the first intake cam 16 while maintaining a certain distance from the pin 45.

  The swing cam arm 50 is formed with a spring seat 50b. One end of a lost motion spring 38 is hung on the spring seat 50b. The other end of the lost motion spring 38 is fixed to a stationary part of the internal combustion engine. The lost motion spring 38 is a compression spring. Due to the biasing force received from the lost motion spring 38, the slide surface 50 a of the swing cam arm 50 is pressed against the second roller 53, and further, the first roller 52 is pressed against the first intake cam 16. As a result, the first roller 52 and the second roller 53 are positioned in a state of being sandwiched between the slide surface 50a and the peripheral surface of the first intake cam 16 from both sides.

  The rocker arm 35 is disposed below the swing cam arm 50. A rocker roller 36 is provided on the rocker arm 35 so as to face the swing cam surface 51. The rocker roller 36 is rotatably attached to an intermediate portion of the rocker arm 35. One end of the rocker arm 35 is in contact with the valve shaft 14 a of the valve 14, and the other end of the rocker arm 35 is rotatably supported by a hydraulic lash adjuster 37. During the lift operation, the valve shaft 14a is urged in a closing direction, that is, a direction in which the rocker arm 35 is pushed up by a valve spring (not shown). The rocker roller 36 is pressed against the swing cam surface 51 of the swing cam arm 50 by the biasing force and the hydraulic lash adjuster 37.

  According to the configuration of the variable valve mechanism 40 described above, the pressing force of the first intake cam 16 is transmitted to the slide surface 50 a via the first roller 52 and the second roller 53 as the first intake cam 16 rotates. Is done. As a result, when the contact point between the rocking cam surface 51 and the rocker roller 36 extends from the non-operation surface 51a to the operation surface 51b, the rocker arm 35 is pushed down and the valve 14 is opened.

  Further, according to the configuration of the variable valve mechanism 40, when the rotational position of the control shaft 41 is changed, the position of the second roller 53 on the slide surface 50a changes, and the swing cam arm 50 swings during the lift operation. The range changes. More specifically, when the control shaft 41 is rotated in the counterclockwise direction in FIG. 3, the position of the second roller 53 on the slide surface 50 a moves to the tip side of the swing cam arm 50. Then, the rotation angle of the swing cam arm 50 that is actually required until the rocker arm 35 starts to be pressed after the swing cam arm 50 starts swinging by transmitting the pressing force of the first intake cam 16 is: The control shaft 41 becomes larger as it rotates counterclockwise in FIG. That is, the operating angle and lift amount of the valve 14 can be reduced by rotating the control shaft 41 counterclockwise in FIG. Conversely, the operating angle and lift amount of the valve 14 can be increased by rotating the control shaft 41 in the clockwise direction.

  As described above, the variable valve mechanism 40 of the present embodiment makes both the operating angle and the lift amount of the valve 14 variable. In this specification, the operating angle and the lift amount are collectively referred to as “valve opening amount”. Note that the variable valve mechanism in the present invention may be one in which either the operating angle or the lift amount is variable.

(2) Detailed Configuration of Fixed Valve Mechanism Next, a detailed configuration of the fixed valve mechanism 70 will be described with reference to FIGS. 2 and 4. FIG. 4 is an exploded perspective view showing the variable valve mechanism 40 and the fixed valve mechanism 70 shown in FIG.

  As shown in FIG. 2, the fixed valve mechanism 70 is interposed between the second intake cam 17 and the second swing cam arm 50R. The fixed valve mechanism 70 interlocks the swing motion of the second swing cam arm 50 </ b> R with the rotational motion of the second intake cam 17. The fixed valve mechanism 70 includes a large lift arm 71 driven by the second intake cam 17 and an arm coupling mechanism 72 (see FIG. 4) for coupling the large lift arm 71 to the second swing cam arm 50R. . The arm coupling mechanism 72 includes a switching pin 74, a hydraulic chamber 75, a pin hole 76, a return spring 77, and a piston 78, which will be described later.

  The large lift arm 71 is arranged on the control shaft 41 along with the second swing cam arm 50R, and can swing independently of the second swing cam arm 50R. An input roller 73 that contacts the peripheral surface of the second intake cam 17 is rotatably supported on the large lift arm 71.

  As shown in FIG. 4, a spring seat 71 a is formed on the large lift arm 71. As with the swing cam arm 50, a lost motion spring (not shown) is hung on the spring seat 71a. The input roller 73 is pressed against the peripheral surface of the second intake cam 17 by the spring force of the lost motion spring.

  The large lift arm 71 includes a switching pin 74 that can be taken in and out toward the second swing cam arm 50R. The large lift arm 71 is formed with a hydraulic chamber 75 having an opening on the second swing cam arm 50R side. A switching pin 74 is fitted in the hydraulic chamber 75. The hydraulic chamber 75 is connected to a hydraulic system described later. When the hydraulic pressure in the hydraulic chamber 75 is increased by the hydraulic system, the switching pin 74 is pushed out from the hydraulic chamber 75 toward the second swing cam arm 50R by the hydraulic pressure.

  On the other hand, a pin hole 76 having an opening on the large lift arm 71 side is formed in the second swing cam arm 50R. The switching pin 74 and the pin hole 76 are formed at positions where the distance from the center of the control shaft 41 is equal. A return spring 77 and a piston 78 as a lifter are disposed in the pin hole 76 from the back side.

FIG. 5 is a schematic diagram showing a configuration of a hydraulic system for operating the switching pin 74.
As shown in FIG. 5, an oil passage 81 is formed in the control shaft 41. The oil passage 81 is connected to the hydraulic chamber 75, a sliding gap between the control shaft 41 and the large lift arm 71, and a sliding gap between the control shaft 41 and the second swing cam arm 50R. The oil passage 81 is connected to a pump 82. A discharge path 83 is connected in the middle of the oil path 81. A discharge valve 84 is provided in the discharge path 83. Further, an orifice 85 is provided downstream of the discharge valve 84 in the discharge path 83.

  The lubricating oil pressurized by the pump 82 is supplied to the sliding gap through the oil passage 81. A part of the lubricating oil flowing through the oil passage 81 is supplied to the hydraulic chamber 75. Therefore, the hydraulic pressure in the hydraulic chamber 75 can be increased. On the other hand, when the discharge valve 84 is opened, the lubricating oil is discharged from the discharge path 83. Thereby, the hydraulic pressure in the hydraulic chamber 75 can be lowered. The switching pin 74 can be operated by controlling the hydraulic pressure in the hydraulic chamber 75.

[Features of Embodiment 1]
(Single valve variable state)
The large lift arm 71 is always oscillated by being driven by the second intake cam 17. However, during the period in which the base circle portion of the second intake cam 17 is in contact with the input roller 73, the large lift arm 71 stops instantaneously. Yes. The second swing cam arm 50R is also driven to swing by the first intake cam 16, but during the period when the base circle portion of the first intake cam 16 is in contact with the first roller 52, the second swing cam arm 50R is instantaneous. Still. The rest period of both overlaps. That is, there is a period in which the large lift arm 71 and the second swing cam arm 50R are stationary simultaneously.

  The angle of the second swing cam arm 50 </ b> R in the stationary state changes according to the rotational position of the control shaft 41. Therefore, there is a rotational position of the control shaft 41 that allows the position of the switching pin 74 and the position of the pin hole 76 to coincide with each other in the stationary state of the large lift arm 71 and the second swing cam arm 50R. The rotational position of the control shaft 41 is hereinafter referred to as “pin switching position”. That is, in the valve mechanism 18, the position of the pin hole 76 and the position of the switching pin 74 can be matched by setting the rotational position of the control shaft 41 to the pin switching position. Therefore, in this state, the switching operation of the arm coupling mechanism 72 can be executed as follows.

  When the position of the pin hole 76 coincides with the position of the switching pin 74, the switching pin 74 contacts the piston 78. At this time, if the hydraulic pressure in the hydraulic chamber 75 is larger than the force that pushes the switching pin 74 than the force that the return spring 77 pushes the piston 78, the switching pin 74 pushes the piston 78 into the back of the pin hole 76. Then, it enters the pin hole 76. That is, the switching pin 74 can be inserted into the pin hole 76 by increasing the hydraulic pressure in the hydraulic chamber 75 by the hydraulic system. When the switching pin 74 is inserted into the pin hole 76, the second swing cam arm 50R and the large lift arm 71 are connected. Thereby, the interlocking destination of the lift movement of the second intake valve 14R can be switched from the variable valve mechanism 20R to the fixed valve mechanism 70.

  In this case, the rotational motion of the intake cam shaft 15 is transmitted from the second intake cam 17 via the large lift arm 71 to the second swing cam arm 50R. The opening amount of the second intake valve 14R is mechanically determined by the shape and positional relationship of the second intake cam 17, the large lift arm 71, and the second swing cam arm 50R, and is always constant regardless of the rotational position of the control shaft 41. The valve opening amount (large lift and large working angle) is fixed. On the other hand, the rotational motion of the first intake cam 16 is transmitted from the first intake cam 16 to the first swing cam arm 50L via the first roller 52 and the second roller 53L. Therefore, the valve opening amount of the first intake valve 14L changes in conjunction with the rotational position of the control shaft 41.

  In this specification, the state in which the valve opening amount of the second intake valve 14R is fixed to the large valve opening amount and only the valve opening amount of the first intake valve 14L changes in accordance with the rotational position of the control shaft 41 in this specification. This is called “one-valve variable state”. In the one-valve variable state, the second intake valve 14R can be a large lift and the first intake valve 14L can be a small lift. Thereby, a large amount of air flows from the second intake valve 14R and a small amount of air flows from the first intake valve 14L into the cylinder. Due to the deviation of the inflow amount, a swirl flow (swirl flow) can be formed in the cylinder. By forming a swirl flow, combustion can be improved in a low rotation / low load range.

(Both valves variable state)
On the other hand, when the position of the pin hole 76 coincides with the position of the switching pin 74, the switching pin 74 can be removed from the pin hole 76 by lowering the hydraulic pressure in the hydraulic chamber 75. Thereby, the connection between the large lift arm 71 and the second swing cam arm 50R is released. Therefore, the interlocking destination of the lift movement of the second intake valve 14R can be switched from the fixed valve mechanism 70 to the variable valve mechanism 20R.

  In this case, the rotational motion of the cam shaft 15 is transmitted from the first intake cam 16 to the slide surfaces 50a of the first and second swing cam arms 50L, 50R via the first and second rollers 52, 53. The Therefore, the valve opening amounts of the first intake valve 14L and the second intake valve 14R both change in conjunction with the rotation of the control shaft 41. Therefore, the valve opening amount of the first intake valve 14L and the valve opening amount of the second intake valve 14R can be changed together according to the rotational position of the control shaft 41. In this specification, the state in which the opening amounts of the first intake valve 14L and the second intake valve 14R are uniform and variable is referred to as a “both valve variable state” in this specification.

  The ECU 60 switches between the two-valve variable state and the one-valve variable state according to the operating state of the internal combustion engine 1 (specifically, the engine speed NE and the load). FIG. 6 is a diagram showing a switching map between the both-valve variable state and the one-valve variable state, which is stored in the ECU 60. In this switching map, the operating range of the internal combustion engine 1 is represented by taking the engine speed NE on the horizontal axis and the load on the vertical axis.

  Here, “load” means any index having a correlation with the load of the internal combustion engine 1, such as the torque of the internal combustion engine 1, the load factor, or the accelerator opening AA. The ECU 60 can calculate the load value based on sensor outputs from the accelerator opening sensor 24, the air flow meter 26, and the like. Further, the ECU 60 can calculate the engine speed NE based on the output of the crank angle sensor 6. In this way, the ECU 60 can detect where the current operating state of the internal combustion engine 1 is in the switching map.

  In FIG. 6, a switching pin operation line P represents a boundary where switching between the both-valve variable state and the one-valve variable state is performed. In FIG. 6, two circles arranged side by side represent the first intake valve 14L and the second intake valve 14R, and the letters in the circles represent the amount of valve opening.

  As shown in FIG. 6, the region on the low rotation / low load side from the switching pin operating line P is a region where the one-valve variable state is set. This region is referred to as a “one-valve small lift region” in this embodiment. In the single valve small lift region, the switching pin 74 of the arm connecting mechanism 72 is connected to the pin hole 76.

  On the other hand, the region on the high rotation / high load side of the switching pin operating line P is a region where both valves are variable. This region is referred to as a “double-valve large lift region” in this embodiment. In this double valve large lift region, the switching pin 74 of the arm coupling mechanism 72 is removed from the pin hole 76, that is, in a non-coupled state.

  The ECU 60 normally switches between the one-valve variable state and the both-valve variable state according to the switching map as described above. In general, combustion tends to be unstable and incomplete in the region of low rotation and low load. On the other hand, in the present embodiment, in the single valve small lift region on the low rotation / low load side, the swirl is formed by setting the second intake valve 14R as a large lift and the first intake valve 14L as a small lift. Combustion can be improved. For this reason, fuel consumption and exhaust emission can be reduced. On the other hand, in the large lift region of both valves on the high rotation / high load side, a sufficient amount of air can be sucked into the cylinder by increasing both lifts of both intake valves 14.

  When the operating state of the internal combustion engine 1 shifts from the one-valve small lift region to the both-valve large lift region, the ECU 60 immediately removes the switching pin 74 from the pin hole 76 and switches to the both-valve variable state. However, even when the operating state has shifted from the single valve small lift region to the double valve large lift region, it may be possible to return to the single valve small lift region again in a short time depending on the situation.

  An example of such a situation is during acceleration after the vehicle starts. Before starting the vehicle, the internal combustion engine 1 is in an idling state indicated by a point A in FIG. After starting at the first speed, as the vehicle accelerates, the driving state changes from point A → B in FIG. 6 and further from point B → C. Thereafter, to shift up to the second speed, the clutch is disengaged and the accelerator pedal is released. As a result, the operating state of the internal combustion engine 1 returns to the idling state, and thus returns to the point C → A.

  The same change as described above occurs when shifting up to the third speed and the fourth speed. That is, at the time of acceleration after the vehicle starts, the operating state of the internal combustion engine 1 circulates from point A → B → C → A in FIG. 6 within a relatively short time. In such a case, if the switching operation of the arm coupling mechanism 72 is performed immediately according to the switching map shown in FIG. 6, the switching pin 74 is removed from the pin hole 76 at the point B → C, and then the point C → At A, the switching pin 74 is reinserted into the pin hole 76. That is, the time during which the variable state of both valves is maintained at points B → C → A is extremely short. For this reason, there are few merits to switch to a both-valve variable state. Rather, there is a greater demerit that the switching pin 74 and the pin hole 76 are worn or damaged due to frequent insertion and removal of the switching pin 74. Therefore, in the present embodiment, in view of the durability of the arm coupling mechanism 72, the switching operation of the switching pin 74 is not performed in the above case.

  The switching operation to be avoided as described above is accompanied by a shift of the transmission. Therefore, in this embodiment, in order to identify and avoid the switching operation associated with the shift, the switching operation of the arm coupling mechanism 72 is temporarily prohibited within a predetermined time immediately after the shift of the transmission. .

  According to the processing as described above, it is possible to identify and avoid a switching operation with low necessity not only during acceleration after the vehicle starts but also in the following situation. Changes in points D to K in FIG. 7 indicate changes in the driving state when the vehicle approaches an uphill during high speed traveling. In this case, the operating state of the internal combustion engine 1 changes as follows. When the vehicle approaches an uphill, the vehicle speed gradually decreases due to the uphill resistance, and accordingly, the engine speed NE also gradually decreases (D → E). Then, the driver performs a downshift operation in order to recover the vehicle speed. When the clutch is disengaged and the accelerator pedal is released due to this shift-down operation, the internal combustion engine 1 changes toward an idle state (E → F). After the downshift, when the accelerator pedal is depressed, the internal combustion engine 1 changes to a high rotation / high load state (F → G). As the acceleration continues, the engine speed NE increases (G → H). When the vehicle speed is sufficiently recovered, the driver performs a shift-up operation. When the clutch is disengaged and the accelerator pedal is released due to this shift-up operation, the internal combustion engine 1 changes toward an idle state (H → I). After the upshift, the engine speed NE is lower than that before the upshift (I → J). Thereafter, steady operation is performed at this gear position (J → K).

  In such a situation, if the switching operation of the arm coupling mechanism 72 is immediately performed according to the switching map shown in FIG. 7, the switching pin 74 is removed from the pin hole 76 by F → G, and then H → I. The switching pin 74 is reinserted into the pin hole 76. Also in this case, since the time during which the both-valve variable state is maintained is extremely short, there are few merits to switch to the both-valve variable state. . That is, it can be said that the switching operation in this case should also be avoided. According to the present embodiment, the execution of the shift performed at the point F is detected, and then the switching operation of the arm coupling mechanism 72 within a predetermined time is temporarily prohibited so that the switching operation to be avoided is not performed. Can be.

[Specific Processing in Embodiment 1]
FIG. 8 is a flowchart of a routine executed by the ECU 60 in the present embodiment in order to realize the above function. Note that this routine is periodically executed at predetermined time intervals. According to the routine shown in FIG. 8, it is first determined whether or not the transmission has been changed (step 100). Whether or not the shift is performed can be detected by the shift position sensor 62. If it is determined in step 100 that no speed change is being performed, it is not necessary to prohibit the switching operation of the arm coupling mechanism 72, so the following processing is not performed. In this case, normal control is performed in which the switching between the one-valve variable state and the both-valve variable state is immediately performed according to the switching map.

  On the other hand, if it is determined in step 100 that a shift has been performed, then the operating state of the internal combustion engine 1 changes from the one-valve small lift area to the double-valve large lift area within a predetermined time from the execution of the shift. It is determined whether or not it has changed (step 102). The predetermined time here is determined based on data obtained by investigating the time required for the change of B → C → A in FIG. 6 and the change of F → G → H → I in FIG. Is remembered.

  If no change from the single valve small lift area to the double valve large lift area is recognized in step 102, it means that the switching command for the arm coupling mechanism 72 has not been issued. In this case, since it is not necessary to inhibit the switching operation, the following processing is not performed and normal control is continued.

  On the other hand, when a change from the single valve small lift region to the double valve large lift region is recognized in step 102, the switching operation of the arm coupling mechanism 72 is prohibited (step 104). That is, although the operating state of the internal combustion engine 1 has shifted to the double-valve large lift region, the switching pin 74 remains inserted in the pin hole 76, and switching to the dual-valve variable state is not executed. When a change from the single valve small lift region to the double valve large lift region is recognized in step 102, the change corresponds to a change such as B → C in FIG. 6 or F → G in FIG. It is expected to return to the single valve small lift region within a short time. According to the processing in step 104, the switching operation in such a case can be avoided.

  In the routine shown in FIG. 8, it is next determined whether or not the elapsed time from the change of the operating state from the single valve small lift region to the double valve large lift region has reached a predetermined time (step 106). In this embodiment, the process of step 104 described above avoids switching to the two-valve variable state in anticipation of returning to the single valve small lift region in a short time. However, depending on the driving conditions of the vehicle and the operation contents of the driver, there is a case where the valve does not return to the one-valve small lift region immediately but remains in the double-valve large lift region. In such a case, it is desirable to switch to the two-valve variable state in order to make the internal combustion engine 1 perform its intended performance. Therefore, in the present embodiment, if the elapsed time after the change to the double valve large lift region in step 106 has reached a predetermined time but has not returned to the single valve small lift region, the processing of this routine is terminated. (RETURN) to return to normal control. By returning to the normal control, the switching operation to the both-valve variable state is executed according to the switching map. The predetermined time here is usually about several seconds to several tens of seconds, although the preferred value varies depending on the type of the internal combustion engine 1 and the use of the mounted vehicle.

  In the routine shown in FIG. 8, it is next determined whether or not the operating state has changed to a region other than the single valve small lift region and the double valve large lift region (step 108). Here, the area other than the single valve small lift area and the double valve large lift area refers to the double valve variable lift area. The both-valve variable lift region is a region in which the lift amount of both intake valves 14 is variably controlled from the middle lift to the small lift in the both-valve variable state. This double-valve variable lift region is set for the purpose of, for example, improving the engine brake when the internal combustion engine 1 is decelerated. The range of the double valve variable lift region is stored in the ECU 60 separately from the switching map.

  If the operating state has changed to the double-valve variable lift region in step 108, the processing of this routine is terminated (RETURN) and the routine returns to normal control. By returning to the normal control, the switching operation to the both-valve variable state is executed based on a predetermined rule. The double-valve variable lift region can be set as needed not only during deceleration, but also during light load operation, idling, cold start, cold, and the like.

  In the routine shown in FIG. 8, it is next determined whether or not the operating state has returned from the double valve large lift region to the single valve small lift region (step 110). At this time, the execution of switching to the both-valve variable state is prohibited by the processing of step 104 above. Under this circumstance, when the operating state returns to the one-valve small lift region, there is no need to switch to the both-valve variable state, so there is no need to prohibit the switching operation. Therefore, in this case, the processing of this routine is terminated (RETURN) and the routine returns to normal control. On the other hand, if the operating state is still in the double-valve large lift region at step 110, the processing after step 106 is executed again.

  According to the processing described above, when it is less necessary to perform the switching operation of the arm coupling mechanism 72, the switching operation is prohibited. For this reason, it can avoid that the arm connection mechanism 72 wears more than necessary, and the durability of the arm connection mechanism 72 can be improved.

  In the first embodiment described above, the shift position sensor 62 detects the shift of the transmission, but the shift detection method is not limited to this. For example, a clutch sensor that detects the engagement / disengagement of the clutch may be provided, and the execution of the shift may be detected when the clutch is disengaged (in the case of a manual transmission). Alternatively, the execution of the shift can be detected based on the ratio between the engine speed NE and the vehicle speed. Since the vehicle speed sensor is normally installed in any vehicle, according to the method using such a vehicle speed, the execution of the shift can be detected without adding a new sensor.

  Further, in the first embodiment described above, the execution of the switching operation when shifting from the single valve small lift region to the double valve large lift region under a predetermined situation is prohibited. In the present invention, on the contrary, In addition, it is possible to prohibit the execution of the switching operation when the both valve large lift region shifts to the single valve small lift region.

  In the first embodiment described above, the valve opening amounts of the first intake valve 14L and the second intake valve 14R (when both valves are variable) or the valve opening amount of the first intake valve 14L (one valve variable state). Has been described by way of example, but the present invention is also applicable to a valve operating mechanism in which these valve opening amounts are variable in multiple stages (multiple stages). Can do.

  Further, in the first embodiment described above, the case where the present invention is applied to a variable valve operating apparatus for an intake valve has been described, but the present invention can also be applied to a variable valve operating apparatus for an exhaust valve.

  In addition, each said modification is applicable similarly also in other embodiment demonstrated below.

  In the first embodiment described above, the single valve small lift region is the “single valve variable region” in the first invention, and the double valve large lift region is the “double valve variable region” in the first invention. The arm coupling mechanism 72 corresponds to the “switching mechanism” in the first invention, and the ECU 60 corresponds to the “storage means” in the first invention. Further, when the ECU 60 causes the arm coupling mechanism 72 to perform a switching operation according to the switching map, the “normal control means” in the first invention executes the processing of the steps 100 and 102 described above, thereby causing the first invention. When the “situation judging means” in step 1 executes the process of step 104, the “inhibiting means” in the first invention executes the process of step 106, thereby “prohibiting in the fourth invention”. "Release means" are realized respectively.

Embodiment 2. FIG.
[Features of Embodiment 2]
Next, the second embodiment of the present invention will be described with reference to FIG. 9. The description will focus on the differences from the above-described embodiment, and the description of similar matters will be omitted or simplified. . The system of the present embodiment can be realized by causing the ECU 60 to execute a routine shown in FIG. 9 to be described later using the same hardware configuration as that of the first embodiment.

  When the driver depresses the accelerator pedal when the vehicle is stopped, the internal combustion engine 1 may be caused to perform a free accelerator operation (so-called idling). This free accelerator operation is rarely performed for a long time. Therefore, even when the operating state changes from the single valve small lift region to the double valve large lift region during the free accelerator operation, it is expected to return to the single valve small lift region in a short time. Therefore, in this embodiment, also in this case, the execution of switching to the both-valve variable state is avoided, and the durability of the arm coupling mechanism 72 is improved.

[Specific Processing in Second Embodiment]
FIG. 9 is a flowchart of a routine executed by the ECU 60 in the present embodiment in order to realize the above function. According to the routine shown in FIG. 9, first, it is determined whether or not the shift position of the transmission is in the neutral (in the case of a manual transmission or an automatic transmission) or the parking range (in the case of an automatic transmission). Is determined based on the output (step 120). When the shift position is not in the neutral or parking range, the free accelerator operation is not performed, so the following processing is not executed.

  In step 120, if the shift position is in the neutral or parking range, it is next determined whether or not the operating state of the internal combustion engine 1 has changed from the single valve small lift region to the double valve large lift region ( Step 122). When a change to the double-valve large lift region is recognized, it can be determined that the free accelerator operation is being performed. Therefore, in this case, the switching operation of the arm coupling mechanism 72 is prohibited (step 124). That is, although the operating state of the internal combustion engine 1 has shifted to the double-valve large lift region, the switching pin 74 remains inserted in the pin hole 76, and switching to the dual-valve variable state is not executed.

  In the routine shown in FIG. 9, it is then determined whether or not the operating state has changed to a region other than the double valve large lift region, that is, the single valve small lift region or the double valve variable lift region (step 126). If a change to a region other than the double-valve large lift region is recognized, it can be determined that the free accelerator operation has ended, so this routine ends and the normal control is returned (RETURN). On the other hand, when the change to the area other than the double valve large lift area is not recognized, it can be determined that the free accelerator operation is continued. In this case, the process returns to step 124 and the switching operation prohibition state is maintained.

  According to the processing as described above, it is possible to avoid the arm coupling mechanism 72 from performing a switching operation unnecessarily during the free accelerator operation, and the durability of the arm coupling mechanism 72 can be improved.

Embodiment 3 FIG.
[Features of Embodiment 3]
Next, a third embodiment of the present invention will be described with reference to FIG. 10. The description will focus on differences from the above-described embodiments, and the description of similar matters will be omitted or simplified. . The hardware configuration of this embodiment is the same as that of the first embodiment. The system of the present embodiment can be realized by causing the ECU 60 to execute a routine shown in FIG. 10 described later in addition to the processing of the first or second embodiment.

  As described above, in the arm coupling mechanism 72, the switching pin 74 is moved by the hydraulic pressure of the lubricating oil of the internal combustion engine 1. As the internal combustion engine 1 continues to operate, sludge (viscous material) may be generated in the lubricating oil. If the switching pin 74 does not operate for a long time with the sludge adhering to the periphery of the switching pin 74, the switching pin 74 is fixed in the hydraulic chamber 75 or the pin hole 76 and operated. It may be impossible.

  In the first and second embodiments, as described above, the switching operation of the arm coupling mechanism 72 is prohibited in a fixed case. For this reason, the opportunity to perform the switching operation of the arm coupling mechanism 72 is reduced. If the opportunity to perform the switching operation of the arm coupling mechanism 72 is reduced, a state in which the switching pin 74 is not moved for a long time is likely to occur, and as a result, the possibility that the switching pin 74 is fixed by sludge increases.

  Therefore, in this embodiment, when the number of times of prohibition of the switching operation of the arm coupling mechanism 72 or the cumulative time of prohibition exceeds a predetermined value, the switching operation is permitted to prevent the switching pin 74 from sticking. .

[Specific Processing in Embodiment 3]
FIG. 10 is a flowchart of a routine executed by the ECU 60 in the present embodiment in order to realize the above function. The routine shown in FIG. 10 is executed in conjunction with the routine shown in FIG. 8 or FIG.

  In the routine shown in FIG. 10, the number of times that the switching operation of the arm coupling mechanism 72 is prohibited by the processing shown in FIG. 8 or 9 and the accumulated time are measured, and the number and time are stored in the ECU 60. (Step 130). Then, it is determined whether or not any of the number of times of prohibition and the accumulated time has exceeded a predetermined value for each (step 132). The predetermined value here is a value determined according to the characteristics of the internal combustion engine 1 and the mounted vehicle, and is stored in the ECU 60 in advance. This value is set so that the switching operation can be surely performed before the switching pin 74 is fixed.

  If any of the number of prohibitions and the accumulated time exceeds the predetermined value in step 132, the routine control (switching prohibition control) shown in FIG. 8 or FIG. 9 is stopped and the control returns to the normal control (step 134). In the normal control, the switching operation of the arm coupling mechanism 72 is executed according to the switching map.

  Next, in normal control, it is determined whether or not the switching operation of the arm coupling mechanism 72 has actually been performed (step 136). When the switching operation of the arm coupling mechanism 72 is actually performed, the prevention of the fixing of the switching pin 74 is achieved. In this case, the suspension of the switching prohibition control by the routine shown in FIG. 8 or FIG. 9 is canceled, and the switching prohibition control is returned to a state where it can be executed (step 138). Along with this, the number of prohibitions and the accumulated time stored in step 130 are reset to zero. In the above processing, it is determined whether or not to return to the state in which the switching prohibition control can be executed based on whether or not the switching operation of the arm coupling mechanism 72 is actually performed. The method is not limited to this. That is, this determination may be made based on whether or not there is an instruction to switch the arm coupling mechanism 72.

  According to the processing as described above, when performing the processing of the first embodiment or the second embodiment, it is possible to reliably prevent the switching pin 74 from sticking due to a decrease in the switching operation execution opportunity of the arm coupling mechanism 72. Can do.

  In the third embodiment described above, the ECU 60 executes the process of step 130, so that the “measurement means” in the fifth aspect of the invention executes the processes of steps 132 and 134. The “allowing means” in the fifth invention is realized.

Embodiment 4 FIG.
[Features of Embodiment 4]
Next, the fourth embodiment of the present invention will be described with reference to FIG. 11. The description will focus on the differences from the above-described embodiment, and the description of the same matters will be omitted. The hardware configuration of this embodiment is the same as that of the first embodiment. And this embodiment shall perform the process similar to Embodiment 1 or 2 fundamentally.

  FIG. 11 is a diagram illustrating valve lifts (lift curves) of the first intake valve 14L and the second intake valve 14R. In the present embodiment, when both valves are variable, the valve lift of the first intake valve 14L and the valve lift of the second intake valve 14R are substantially equal. The valve lifts A to E in FIG. 11 are the following valve lifts, respectively.

  The valve lift A is the maximum valve lift in the double valve large lift region (both valve variable state). This valve lift is set in advance based on the maximum output performance requirement for the internal combustion engine 1.

  The valve lift B is in a state where the rotational position of the control shaft 41 is at the pin switching position, that is, in a state where the position of the switching pin 74 and the position of the pin hole 76 coincide with each other, and the large lift arm 71 and the second swing cam arm. This is a valve lift in a state where the 50R is not connected.

  The valve lift C is a valve of the second intake valve 14R in a state where the large lift arm 71 and the second swing cam arm 50R are connected and the second intake valve 14R is fixed at a large valve opening amount, that is, in a one-valve variable state. It is a lift.

  The valve lift D is the minimum valve lift that can be set by the variable valve mechanism 40. The valve lift E is the maximum valve lift that can be set by the variable valve mechanism 40. In the present embodiment, since the valve lift A is the upper limit of the use range, the valve lift E is not actually used.

  In the single valve small lift region, the target valve lift is set in a range from the valve lift D to the valve lift B. That is, in the one-valve small lift region, the target position of the control shaft 41 is set to a range on the small lift small operating angle side from the pin switching position. On the other hand, in the double valve large lift region, the target valve lift is set in a range from the valve lift B to the valve lift A. That is, in the double valve large lift region, the target position of the control shaft 41 is a range from the pin switching position corresponding to the valve lift B to the position corresponding to the valve lift A on the large lift large working angle side. .

  As described above, the upper limit of the target valve lift in the single valve small lift region is the valve lift B. In the normal control, a one-valve variable state, that is, a state where the large lift arm 71 and the second swing cam arm 50R are connected is realized in the one-valve small lift region. Therefore, when the valve mechanism 18 is in the one-valve variable state, the range below the valve lift B is normally controlled as the target valve lift.

  On the other hand, in the first embodiment and the second embodiment, as described above, even when the single valve small lift region is shifted to the double valve large lift region, the single valve variable state is changed to the double valve variable state. Switching operation is prohibited and the one-valve variable state may be maintained (step 104 in FIG. 8 or step 124 in FIG. 9). For this reason, a target valve lift larger than the valve lift B may be set when the valve mechanism 18 is in the one-valve variable state. In such a case, the following situation occurs.

  In the one-valve variable state, as described above, normally, the second intake cam 17 drives the large lift arm 71, and the large lift arm 71 drives the second swing cam arm 50R via the switching pin 74. Yes. However, in the one-valve variable state, when the control shaft 41 is rotated to the large lift large operating angle side beyond the pin switching position corresponding to the valve lift B, the second intake cam 17 swings the second swing cam arm 50R. Since the range in which the first intake cam 16 swings the second swing cam arm 50R is larger than the range in which the second swing cam arm 50R is moved, the second swing cam arm 50R reversely drives the large lift arm 71 via the switching pin 74. It becomes a state to do. For this reason, in this state, the input roller 73 of the large lift arm 71 is separated from the second intake cam 17.

  Thus, when the engine speed NE and the load are suddenly reduced from the state in which the input roller 73 of the large lift arm 71 is separated from the second intake cam 17, the control shaft 41 instantaneously moves to the small lift small working angle side. It is rotated. Then, the input roller 73 of the large lift arm 71 and the second intake cam 17 come into contact with each other (collision), and noise is generated by the impact, or the surfaces of the input roller 73 and the second intake cam 17 are damaged. There is a fear.

  Therefore, in the present embodiment, in order to prevent the above situation, the switching operation from the one-valve variable state to the both-valve variable state is prohibited (step 104 in FIG. 8 or step 124 in FIG. 9). ), That is, when the both valve large lift region is entered while being maintained in the single valve variable state, the target valve lift is limited to the valve lift B or less. Thereby, it is possible to prevent the control shaft 41 from rotating beyond the pin switching position corresponding to the valve lift B to the large lift large operating angle side when the valve mechanism 18 is in the one-valve variable state. Therefore, it is possible to reliably prevent a situation in which the input roller 73 of the large lift arm 71 is separated from the second intake cam 17. For this reason, it can prevent more reliably that noise generate | occur | produces or the surface of the input roller 73 and the 2nd intake cam 17 is damaged.

  In the present embodiment, as described above, since the original target valve lift in the both-valve large lift region is in the range from the valve lift B to the valve lift A, switching from the one-valve variable state to the both-valve variable state is performed. If the operation is prohibited, the target valve lift is fixed to the valve lift B in practice if it is limited to the valve lift B or less.

  Since this embodiment is the same as Embodiment 1 or 2 except for the points described above, further description is omitted.

  In the fourth embodiment described above, when ECU 60 is prohibited from switching from the one-valve variable state to the both-valve variable state (step 104 in FIG. 8 or step 124 in FIG. 9), By restricting the valve lift (target valve opening amount) to be equal to or less than the valve lift B, the “valve opening restricting means” in the sixth and seventh inventions is realized. The first intake valve 16 is the “main cam” in the seventh invention, the second intake valve 17 is the “sub cam” in the seventh invention, and the input roller 73 of the large lift arm 71 is the seventh invention. Corresponds to the “partner member” in FIG.

Claims (7)

A both-valve variable state in which the opening amounts of both the first and second valves of the same type provided in the same cylinder are continuously or multistage variable, and the opening amount of the first valve is continuously or multistage. And a valve mechanism having a switching mechanism for switching between a one-valve variable state in which the valve opening amount of the second valve is fixed.
Storage means for storing a rule for distinguishing between the two-valve variable region to be in the both-valve variable state and the one-valve variable region to be in the one-valve variable state among the operation region of the internal combustion engine,
Normal control means for causing the switching mechanism to perform a switching operation according to the rules;
Situation in which it is determined that a predetermined situation is expected to return to the original region in a short time when the operating state of the internal combustion engine shifts from one of the two-valve variable region and the one-valve variable region to the other Judgment means,
When the predetermined situation is established, prohibiting means for prohibiting the switching operation;
A variable valve operating apparatus comprising:   2. The variable valve operating apparatus according to claim 1, wherein the predetermined condition is a condition within a predetermined time from the execution of a shift of a transmission interposed between the internal combustion engine and a drive wheel of the vehicle.   2. The variable valve operating apparatus according to claim 1, wherein the predetermined situation is a situation in which a shift position of a transmission interposed between the internal combustion engine and a drive wheel of a vehicle is in a neutral or parking range.   After the operating state of the internal combustion engine has shifted from one of the two-valve variable region and the one-valve variable region to the other, the switching operation prohibition is lifted if it does not return to the original region even after a predetermined time has elapsed. The variable valve operating apparatus according to any one of claims 1 to 3, further comprising prohibition canceling means. Measuring means for measuring the number of prohibitions by the prohibiting means or the cumulative time of prohibition;
When the number of times of prohibition or the cumulative time of prohibition exceeds a predetermined value, even if the predetermined situation is established, the permitting means for allowing the switching operation of the switching mechanism,
The variable valve operating apparatus according to any one of claims 1 to 4, further comprising:   6. The variable valve operating apparatus according to claim 1, further comprising a valve opening amount limiting unit that limits a target valve opening amount when the switching operation is prohibited by the prohibiting unit. . The valve mechanism is
A main cam that drives both the first valve and the second valve when in the two-valve variable state, and that drives only the first valve when in the one-valve variable state;
A sub-cam for driving the second valve when the one-valve variable state;
Including
The valve opening amount limiting means is configured such that when the switching operation from the one-valve variable state to the both-valve variable state is prohibited by the prohibiting means and maintained in the one-valve variable state, the sub cam and its counterpart member 7. The variable valve operating apparatus according to claim 6, wherein the target valve opening amount is limited to a range in which the two do not separate from each other.

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